我通过PostgreSQL连接器使用Redshift，在php codeigniter 3中查询时出现以下错误。x，php版本7.0模型如下

$subQuery = "select max(button_history_id) as button_history_id  from button_history
        where site_id =".$site_id." group by button_history_id ";

        $this->another->select('cms_group_id');
        $this->another->from('button_history');
        $this->another->where('button_history_id IN ('.$subQuery.")");
        $this->another->where('cms_group_id !=', '');
        $queryGrp = $this->another->get();
        $grpIds = array();
        foreach($queryGrp->result_array() as $grps){
            if($grps['cms_group_id'])
            $grpIds = array_merge($grpIds,explode(',', $grps['cms_group_id']));
        }
        if($grpIds){
            $grpIds = array_unique($grpIds);
            $this->another->select('content_history_id, (content_id),content_name,content_type');
            $this->another->from('content_history');
            $this->another->where_in('content_id',$grpIds);
            $this->another->group_by('content_history_id,content_id,content_name,content_type');
            $this->another->order_by('content_id ,content_history_id',"desc");
            $queryG = $this->another->get();
            $result1 = $queryG->result_array();
        }

但不需要的E'附加在值之前，如下所示
错误：类型“e”不存在

SELECT "content_history_id", (content_id), "content_name", "content_type" FROM "content_history" WHERE "content_id" IN( E'358', E'357', E'359', E'361', E'408', E'398', E'362', E'366', E'363') GROUP BY "content_history_id", "content_id", "content_name", "content_type" ORDER BY "content_id" DESC, "content_history_id" DESC

这个E'358'“E”引起了所有的麻烦，任何人有什么建议请回答。我是新来的，不知道是什么原因，我已经添加了以下信息。
php版本：7.0 codeigniter：3.操作系统：Centos 6.9